This innovative Nitecore NL1834R 18650 battery is an upgrade of the popular Nitecore NL189 18650 battery. It is designed with a built-in micro-USB charging chip and port which effectively eliminates the need for an external charger - you can directly use a standard micro-USB charging cable (sold separately), Simply plug the battery into an available power source using a micro-USB cable and a red indicator light under the + pole (positive) will turn green upon completion. Alternatively, these batteries can still be charged on an external charger if desired. The NL1834R batteries are designed for powering high drain devices such as high-output flashlights, lanterns, headlamps, and bike lights, as well as a variety of other appliances and devices.